Structural highlights
Publication Abstract from PubMedMyxobacteria are able to produce the important metabolite isovaleryl coenzyme A by using an alternative route besides leucine degradation. The first step into this pathway is mediated by LiuC, a member of the 3-methylglutaconyl CoA hydratases (MGCH). Here we present crystal structures refined to 2.05 A and 1.1 A of LiuC in the apo and the coenzyme A bound state, respectively. By using simulated annealing we modeled the enzyme substrate complex and identified residues potentially involved in substrate binding, specificity and catalysis. The dehydration of 3-hydroxy-3-methylglutaconyl CoA to 3-methylglutaconyl CoA catalyzed by LiuC involves Glu112 and Glu132 and likely proceeds via the typical crotonase acid-base mechanism. In this, Tyr231 and Arg69 are key players in positioning the substrate to enable proper catalysis. Surprisingly, LiuC shows higher sequence and structural similarity to human MGCH than to the bacterial form, although they convert the same substrate. This study provides structural insights into the alternative isovaleryl coenzyme A biosynthesis pathway and may open a gate for biofuel research, since isovaleryl CoA is a source for isobutene, a precursor for renewable fuels and chemicals. The structure of LiuC, a 3-hydroxy-3-methylglutaconyl CoA dehydratase involved in isovaleryl CoA biosynthesis in Myxococcus xanthus, reveals insights into specificity and catalysis.,Bock T, Reichelt J, Muller R, Blankenfeldt W Chembiochem. 2016 Jun 8. doi: 10.1002/cbic.201600225. PMID:27271456[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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